Selenium, perhaps the very first material to be studied for its photovoltaic properties, is emerging as an interesting candidate for this application. Indeed Se has a bandgap of around 1.95 eV [1] and a steep increase in absorption above this photon energy. Todorov et al showed [2] in 2017 that single-junction Se solar cells could reach 6.5% efficiency using a new cell architecture with a very thin absorber layer. Recently we have increased the OCV to a new record of 991 mV [2]. Simultaneously, we are also starting to identify the main shortfalls of state-of-the-art Se films which so far have prevented Se-cells from approaching their theoretical potential OCV, which is of course much higher than 991 mV. The talk will introduce Se as a solar absorber and discuss we know about its properties and use in solar devices such as PEC stacks.

[1] T. K. Todorov, S. Singh, D. M. Bishop, O. Gunawan, Y. S. Lee, T. S. Gershon, K. W. Brew, P. D. Antunez and R. Haight, Nature Communications, 2017, 8, 682
[2] R. Nielsen, T. Youngman, H. Moustafa, S. Levcenco, H. Hempel, A. Crovetto, T. Olsen, O. Hansen, I. Chorkendorff, T. Unold, P. C. K. Vesborg, (in preparation), 2022